Chronic Rhinosinusitis (CRS, formerly called chronic sinusitis) is an inflammatory disease of the mucosal lining of the sinuses and the nasal cavity. In the US, 32 million adult patients are estimated to have CRS. Two different kinds of white blood cells, eosinophils and neutrophils, mediate the inflammation. While the eosinophils mediate chronic inflammation, neutrophils mediate acute exacerbations of CRS. The eosinophilic inflammation is directed against fungi, neutrophils are recruited as an immune response against bacteria. Identification of bacterial and/or fungal cause of rhinosinusitis would help physicians in differentiating between acute sinusitis, acute exacerbation of CRS and CRS.
Prior studies have not been successful in accurately predicting a bacterial basis of rhinosinusitis. For example, Grevers et al. (Allergy, 55(12); 1155-1162, December 2000) demonstrated the presence of neutrophils in nasal tissue of patients with CRS. However, we have not found this to be a reliable predictor of bacterial sinusitis.
Hamaguchi et al. (1991A, Acta Otolaryngol., (Stockh), 111(3):542-549; 1991B, Acta Otolaryngol., (Stockh), 111(3):954-959) studied the presence of neutrophils in the mucus of patients with Chronic Sinusitis. All samples were found to be positive for neurtrophile elastase (NE). However, it should be noted that in their analysis, samples were frozen, thawed and then homogenized before analysis for determination of NE. This analysis is therefore flawed in that homogenization would result in breakup of cells and, hence, artifactual release of granule content. Thus, although Hamaguchi et al. refer to measurement of “free” elastase, these authors are not measuring NE released from the neutrophil granules in response to a bacterial sinusitis. Rather, the “free” elastase is a term used in this reference for NE that is not complexed with inhibitors such as α1-antitrypsin. This brings into question the reliability of such identification, particularly in the absence of negative controls.
As a result, there is an ongoing need in the field of sinusitis to identify methods for reliable identification of inflammatory causes such that proper treatment regimen can be implemented by health care providers.